Method for locating sounds.



H. J. FURBER, JR.

W "H [WI [W W illUMHl.

APPLICATION HLED MAR. 4. 1911.

1,149,976. Patented Aug. 10, 1915.

Q9 I I I i a I 5 WW 12 IV V HENRY .T. FURBER, JR OF CHICAGO, ILLINOIS.

FOB momma sormns.

Specification of Letters Patent.

Patented Aug. 10, 1915.

ineman-aged March 4, 1911. No. 612,364.

To all whom it may concern:

Be it known that I, HENRY J. FURBER, J r., a citizen of the United States of America, and resident of Chicago, county of Cook, and State of Illinois, have invented a certain new and useful Method for Locating Sounds, of which the following is a specification.

An object of this invention is to produce a method for ascertaining the point of location of a source of sound.

A further object is to produce a new and improved method of determining the position of a source of sound or vibratory impulses, by measuring the periods of time intervening between the arrival, at three different points of known location, of a sound or vibratory impulse, emanating from the source.

In carrying out my invention, I employ the principle that sound radiating from its source, reaches difierent points at the expiration of intervals of time, which are severally proportional to the distances of the different points from the source pf sound and the known rapidity of propagation in ehe conducting medium or media.

The invention consists in determining the respective moments at which sound, emanating from some source, reaches difi'erent established points, measuring the difference in time at which the sound arrives at said different points and employing the data thus obtained in computing the location of the source of sound.

In the drawings accompanying this application, and forming a part thereof, Figure 1 is a diagrammatic view of apparatus embodying my invention and employed in recording the time at which sound is received at difierent established points. Fig. 2 is a geometric diagram, graphically illustrating the principles employed in the mathematical computation utilized in determining the distance and direction of the source of sound from established points of location. Fig. 3

is a trigonometrical diagram for use in solv-- ing the equations utilized by applicant.

The apparatus illustrated and employed in carrying out the method herein described as an embodiment of my invention, includes three receivers, 3, 4 and 5, which may be simi-' lar in construction to telephone transmitters, and are preferably, for the purpose of simplifying com utation, located in a straight line and at own distances apart, as mdicated at B, C, and A in Fig. 2. Each receiver preferably consists of a diaphragm, which is so arranged that it varies the amount of resistance in an electric circuit, by its fluctuations or vibrations, each receiver being located in an electric circuit, and each circuit including an electro-ma et or solenoid, which actuates the recor ing diaphragm, not shown.

In the drawings, the receiver 3 is located in the same circuit with the solenoid 6, and

the receivers 4 and 5 are respectively located in the circuits of solenoids 7 and 8. Each circuit includes a source of electricity, such as a battery. The solenoids 6, 7 and 8, respectively, actuate pivotally mounted recording arms 9, 10 and 11, through the agency of the recording diaphragms referred to, which fluctuate or vibrate in response to variations in the current passing through the windings of the controlling solenoids. Each armis connected to its operating diaphragm by means of a link 12, and is provided at its free end with a recording pen. adapted to bear against a moving chart. The chart consists of a strip of paper 13, graduated to indicate time units, such, for example, as seconds, and fractions of seconds, and the strip is driven at a uniform and-determined speed. by means of a clock mechanism, not shown. The purpose of this apparatus is to record the time at which sound reaches the different receivers 3, 4 and 5. a

Each vibration of the receiving diaphragm will cause a corresponding vibration of the recording diaphragm and under these conditions, the free ends of the recording arms will reciprocate in response to vibrations of the receiving diaphragms, and will vary in accordance with variations in the intensity of the sound at the receivers.

The invention consists in ascertaining the difl'erence in time at which a sound, emanating from an unknown point, reaches the diflerent receivers 3, 4 and 5, which are respectively located at the established points C, B and A, and then in computing mathematically the position of the point of origin of the sound.

Referring to Fig. 2: Sound emanating from some unknown point of origin, such as reaches the points G, B and A-.-. The diflerence in the periods of elapsed time which i it requires for a certain sound, originating at the unknown source X, to reach successively the points C, B or A, is capable of being represented by lengths of the several radii Co, B?) and Am, the center of whose circlesare respectively at C, B- and A. The velocity of sound in any @certai'n medium is known, and, consequently the to zero.

lengths of those radii are known uantities and may be respectively designate by a, b and 0; In every actual case, one of the three known radii, and possibly two, will be equal zero. Assuming that these centers are located at equal known distances apart along a straight line, the problem thus resolves itself to this: Given, three circles of known radii, whose centers are located at equal and known distances apart, along a straight line, find the radius 7' and center X of a circle which is tangent to all three of the lmown circles.

For simplicity, I refer to Fig. 3, which is a geometric diagram corresponding to Fig. 2. In the diagram the known quantities are the lengths of the lines -Aa, BI) and Co, which are respectively marked a, b and a.

The distance d', that is the distance between adjacent receivers, is also known. Oneobject of the computation is'to find the length of 7", theradius of the unknown circle having its center at X, and the diagram shows the points A, B and C joined with the point -X by means of the respective lines AX, BX and OX. The perpendicular p which passes through the point X is erected on the base line AC, produced, and for'convenience-the portion of. the line between the points C and the point P, at which the perpendicular intersects the production of the base line, is

marked m. The angle APX is a right an 1e and is common to the triangles CPX,B X

T and APX, hence In the right angle triangle CPX +r) =2 II. In the triangle .BPX

+r)=z in which v (b+1-)"= B X; and d+m=BP. III. In the right angle triangle APX -i =P iin which a+r=AX; and (m-i-Qd) =AP. IIV. Subtract equation II from equation I (a+r) (b'+r) =2md+3d V. Subtract equation I from equation III In Fig. 2, the radius Cc equals the line 3, 4 and 5 of the receivers may be established.

It will be observed thatwhile the angle and the distance of X from all points in the line C, B and A can readily be computed by the. computation above described, it' is not thereby determined upon which side of the line AC'the point X is located. To determine this, I preferably provide two addi-.

tional receivers 15 and 16, located on opposite sides of the line C, B and A, and at equal distances from it. When a sound originates on one side of the line, it reaches the receiver 15 first and is indicated by the arm 17, which is actuated through the agency of an electric circuit and a solenoid 18. This will readily indicate that the sound originated on the side of the line on which the receiver 15 is located. When the sound originates on the other side of the line, it reaches the receiver 16 first and is indicated'by the arm '19, which is located in an electric circuit with the receiver 16, and is actuated'by a solenoid 20 and a ma etically controlled diaphragm. With th1s arrangement, it can readily be determined on which side of the line the origin of the sound is located."

' The recording arms 9, 1 0, 11, 17 and 19 will be constantly vibrating, if the receivers controlling them are sufficiently sensitive, and they willconsequently trace zig zag or wavy lines on the chart. Each sound to which the receivers are subjected, will cause a characteristic vibration of the arms, from which any certain sound may be graphically distinguished from all others. These maximum and minimum points may readily be distinguished on the chart, and the difier ence in time between the reception of such a maximum'vibration by one of the receivers and the others will be readily indicated on the chart, and can be determined by measurements or by the graduations on the chart. For example, the stroke of a bell would set up vibrations in the receivers, which might be recorded, as indicated in Fig. 1.

I contemplate employing my invention in navigation, for the purpose of aiding in directing the course of ships during foggy weather, or when it is impossible to employ visual signals. The receivers may be located on shipboard, as for example at known distances apart on the deck of a vessel 23, or means may be provided for locating one or more of the receivers on suitable receptacles, which may be towed behind the vessels. Such a procedure would increase the length of the base line 3, 4: and 5, and would contribute to the accuracy of the results. The receivers 15 and 16 are preferably located at each side of the ship, or extended from the two sides of the ship by means of gaifs. If desired, all or some of the receivers may be submerged, so that the water or air and water may be employed as the medium or media through which the sound is transmitted.

In addition to employing my invention in ascertaining the point of location of a source of sound, I may also employ it in determining the position of an instrument sending wireless telegrams. The receivers would of necessity be different from those employed in ascertaining the position of a source of sound, but the same recording apparatus and the same methods of procedure may be employed, wherever the travel of the waves is measurable. e

In Fig. 1, I have shown a telephone receiver 21 located in the circuit of the sound receiver 5 and the solenoid 8. The purpose of employing this instrument is that the observer may be aided in determining the nature of the sound by hearing it. Each sound to which the receivers are subjected will arms,

cause the recording arms to trace characteristic lines on the strip 13. A chart indicating the character of lines which various sounds will cause the recording arms to trace on the strip may be provided, for the purpose of aiding ing the character of the sound affecting the receivers. This chart could be produced prior to the installation of the apparatus, by subjecting the apparatus to different known sounds, and then making a permanent record of the lines traced by the recording and noting on the record the nature and quality of the sound which each wave line indicates. With such a chart the observer could compare the wave produced on the observer in determin-' the strip of paper 13 with the chart and de termine the character of the sound, Without the aidof the telephone receivers 21.

In accordance with the Unlted States patent statutes, 1 have described a method, and described and illustrated apparatus embodying my invention, but I desire it to be understood that other methods and apparatus may be employed, without departing from the spirit and scope of my invention.

\Vhat I claim is:

1. A method of determining the point of location of a source of sound, which comprises locating sound receivers at known distances apart, determining the time that the sound is received by different receivers, determining the differences between the times of reception of the sound at the different receivers, and employing the diiferences in calculating the distance and direction of the point of location of the sound from the point of location of the receivers.

2. A method of determining the point of location of a source of sound, which comprises line, and a receiver on each side of the line, and determining the time that a sound from the source reaches each receiver.

3. A method of determining the point of location of a source of vibratory impulses, which comprises locating receivers at determined distances apart, determining the times at which the vibrations resulting from a single vibratory impulse arrive at each re ceiver, measuring the periods intervening between the reception of the vibrations at different receivers, and employing the lengths of said periods and the distances between the receivers in computing the position of the source of vibratory disturbance.

4. A method of determining the point of location of a source of sound, which comprises locating three receivers at known distances apart and in a straight line, determining the time at which sound waves initiated by a single vibratory impulse at said source arrive at the different receivers, measuring the length of the periods of time intervening between the arrival of the sound Waves at the different receivers and then computing the position of the source of sound by employing the the sound waves through the intervening medium, the distance between the receivers and the lengths of the intervening periods.

HENRY J. FURBER, JR.

Witnesses:

FRED WAs'oHKE, NELLIE CARLSON.

locating three receivers in a straight rate of travel of 

